Time to improve Tandem

I’ve been using Tandem pumps for 10 years. I like them but I’m annoyed that they are not reinvesting and improving their pumps. The pump is not water resistant but my iPhone is. I hate the mini usb. It time to go to usb3. Bluetooth is feeble at best. iPhone app is far more readable than pump screen but why can’t I change my basal rate or check history or enter a cgm calibration from app on phone? Why can’t I turn phone sideways to get a 24 hour graph? Now Tandem will not support G7 if user only uses basal IQ. Why hasn’t pump been cleared to use fast acting insulin? I’ve done it for years without a problem. It’s hard not to compare to iPhone but the continuous improvement is obvious. Why can’t Tandem test app before a new IOS release. Tandem is now a software company and needs to be responsive and managed like one.

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I say there is plenty that could have easily been changed in the Tslim over the past 5 years especially. That tiny white rubber us older folks or anyone with low vision have to hit dead center, for one. It could be enlarged if that darned cartridge can’t be changed.
The number of hits required for an extended delivery for another. That’s plain ridiculous. And I think the 23 inch tubing should be about 25 or 26. I don’t want the long tubing but the 23 is a couple inches too short. That last isn’t specific to Tslim, I know.
And the silly built in alarms which I know you can change but I still haven’t found a way to turn one of the stupid ones off. The Tslim alarms turnoff, in my view are too hidden and difficult to find. Even searching instructions.
I just don’t find it as user friendly as Medtronic was for me for so many years. The pump cartridge change process, for example. My two cents.

I 100% understand where you’re coming from. I’m an absolute techie and slightly obsessed with medical technology. We all have our vices, and this is mine. I want the new and shiny! But I also understand why things move so slowly and why I’m forced to be patient, even when I don’t want to be.

That said, it’s definitely time for some hardware updates. Thankfully, there’s a whole lot already in the works! Tandem intends to have 3 different pump form factors on the market at the same time in the near future with the Mobi, Sigi, and T:slim X3 all available simultaneously.

I don’t think many people understand just how expensive regulatory approval is for medical devices. Depending on which pathway they have to take, the average cost for a Class II device, which includes insulin pumps, is 31 MILLION USD. That does not include the cost of development and manufacturing, just the FDA portion of the project. That’s also just in the US, and doesn’t account for every other country where Tandem is available.

While pumps may look and feel very similar to cell phones, this alone sets them a world apart. All that expense with much fewer people to split the cost amongst. Things are going to move slowly. There just isn’t a big enough patient base to recoup that cost quickly.

It’s a pretty big deal that Tandem is paying for the more reasonable software update approvals, to keep the innovations coming between big hardware advancements. Tandem was the first to offer this, and the only one consistently rolling out new features.

Basically, Tandem has to do EVERYTHING Apple, Samsung, Google, Motorola, et all… have to do, and then pay an additional tens of millions of dollars to our government overlords for every little advancement.

No. Absolutely not. Tandem is a medical device company that utilizes software well and is bridging the gap between pumps that barely evolved for decades and emerging technology. But never be mistaken that the medical device aspect, and all the government oversight that goes with that, comes first. We really can’t keep comparing insulin pumps to popular consumer electronics. One sustains life and the other sustains pleasure. They are not the same nor remotely comparable.

The micro-usb is my biggest pet peeve about the X2. It’s the primary reason I refused to renew my warranty when it expired 3 years ago. I wanted something new without that annoying plug. I quite enjoy that it’s rechargeable, just not that particular form factor. It’s the last micro-USB relic in my home, and really makes it feel outdated to me. It’s such a tiny thing, but had really diminished my excitement for the pump. USB-C was already available, though not necessarily popular yet, when the X2 was designed and I think it was a pretty bonehead move on their part to overlook the superior charging spec. I’m also annoyed they didn’t put a USB-C plug in the newest pump, but chose to go wireless instead. Meaning slower, less efficient charging, and the need for a special charging base instead of the USB-C cables that are already in every single room of my house and car.

The biggest problem with the X2 wasn’t mentioned, though. It was brilliantly designed with a lot of extra features hidden under the hood, so there was room to grow into their long list of pipeline projects. For instance, there was a second Bluetooth radio laying dormant until December 2019, when it was finally allowed to connect to a cell phone app. And it was built with more processing power than it needed, knowing that automation was coming. Unfortunately, we’re at the end of its capabilities. Tandem did a big R&D Day presentation at the end of 2021, where they basically admitted that the X2 couldn’t handle the heavier AID algorithms of the future, which is the real reason the X3 is being developed.

It absolutely is. It’s rated to be safely submerged at a depth of 1 meter for 30 minutes. That’s not all that different than the newest iPhone 15, which is also rated for 30 minutes submersion, though at a greater depth. I would even consider that quite the accomplishment since the T:slim has a major place of water ingress the iPhone does not: the pump piston. Let’s talk about “waterproof”, though. I know you didn’t use that particular word, but others frequently are. There is no such thing as waterproof! Everything on this earth gives way to water eventually. It’s considered the most powerful force for a reason. “Waterproof” is simply a marketing term. Tandem has chosen to not use that term, no matter what specs their device has. They want to encourage responsible use since our lives are on the line. I mean, really, nobody is going swimming with their new $1,000 iPhone, either. At least they responsibility shouldn’t, since Apple doesn’t warranty against water damage. The “waterproofing” is a safety backup for accidental water exposure, not constant and intentional exposure. The newest Tandem pump coming out, the Mobi, has the same exact water resistance rating as the “waterproof” Omnipod, but they’re still choosing to not use that marketing word to encourage responsible use. I can tell you that my X2 goes swimming very often, though. Gets dropped in the bathtub several times a week, because I’m a clutz, and it’s still going strong after 7 years. I’d take the pump off if I was worried, but my bathtub just isn’t that deep, so I know it’s fine. It’s way more durable than people give it credit for because we’ve all been duped by this idea of “waterproof” and Tandem’s refusal to use that word.

Yes. Absolutely. That’s what Bluetooth is, though. It’s the signal itself that is feeble, not the pump. This is a complaint of every single sensor augmented pump on the market, not just the T:slim. All of the systems revert to your programmed settings if you’re without data for too long. If you look at the data on how often insulin automation is able to run, Tandem is actually doing the best there. (Edit: come to think of it, now that iLet is available, I guess this isn’t true anymore. Now I’ve got to figure out how that works without data!) Bluetooth is incredibly weak and easy to block. That’s the entire reason the FCC allows it’s open use. The signal can’t survive a mere few inches of water, including the water we ourselves are made of. The communication issue is due to us getting in the way of it. Phones are usually farther away so there’s more opportunity for the signal to bounce around and find the mark. They’re also thinner, so there are fewer components blocking the antenna. Bluetooth antennas are very simple and really can’t be improved. The signal is either there or it’s not. There’s no programming on the receiving end that can manufacture information that wasn’t received. The only recourse Tandem has is to put the antenna in a different location. It’s currently behind the screen, which is why it receives data best when the screen is facing out. I feel like most of us would rather the screen faced the body, though, to protect it. So maybe Tandem can move the antenna elsewhere? For the most part, though, I highly believe Bluetooth communication issues will always exist with pumps, just because of how close they are to our water-laden bodies, until we alter our own behavior to better facilitate the communication.

It’s coming! The FDA likes advances in baby steps. Mobile Bolus capability was a major advancement, but only approved in a very limited scope. Full pump control was too much to ask for. Now that we’ve got a few years of safely demonstrated use under our belts, Tandem has been able to ask for expanded mobile capabilities. The new Mobi is entirely controlled by a different cell phone app, including all the features you asked for and more. Eventually, after another one of those multi-million dollar investments for regulatory approval, they’re going to bring this to the T:slim, too. They’ve just got to space things out. There’s a whole lot of expensive projects going on right now with new sensor integrations, the new version of Control-IQ 2.0, 3 new pumps, and the extended wear infusion set.

This is also coming soon. Apidra and Fiasp aren’t even being considered because it’s well known that they crystalize in the pump and cause occlusions. But the clinical trial has already been completed for Lyumjev. There’s just another one of those expensive regulatory approval proccesses in the way. I expect Tandem won’t find it worthwhile to pay such expense for a pump that’s going to be phased out in the near future, but I could be wrong there. The fact that it’s been through a clinical trial is enough for most doctors to be comfortable prescribing Lyumjev off-label for use with the T:slim, even if Tandem themselves aren’t allowed to say so. (The clinical trial would have been stopped if there were major adverse events, so the mere facts that Tandem was confident enough to put it to trial and that it went to completion is enough.) There are a lot of happy campers using Lyumjev with the T:slim already, at least the ones who can tolerate it well. I have complete confidence that the X3 will be indicated for use with Lyumjev, though.

Really excellent answer overall, but I don’t think 2024 is a reasonable expectation for the X3. They haven’t even started clinical trials for it yet, so I highly doubt we’ll see it before 2026. More likely 2027ish. It’s usually a minimum of 3 years from start of trials
to release. I believe the Sigi patch pump will be released first, because that one is starting clinical trials now and has the breakthrough device designation. Entirely speculation on my part, though, since Tandem’s CEO always dodges the question when asked. I expect we’ll hear more on the timeline after the Mobi and Libre 2 integration launches are cleared from the pipeline and they need to start taking about new projects more.


I agree it’s kind of a pain to hit that little thing, but officially they do say it doesn’t have to be dead center, and it’s not a problem if it misses the detente and goes all the way to the full depth of the needle. I’ve done that quite a few times. A couple of times I have had that glitch where the syringe needle won’t depress. Freaked me out the first time, called Tandem support, and they said just withdraw it from the cartridge, squirt a little insulin out to make sure the needle isn’t blocked, then give it another try. That worked for me.

Officially, yah, but this was my first question when considering Tandem as I’ve been on Fiasp for years, and my trainer reassured me she uses Fiasp (like a lot of Tandem pumpers) without any problems. It’s technically off-label, and you’re probably right that there may be a concern about failing FDA on that basis so they just don’t want to take that risk. But practically speaking it’s pretty common and my only occlusions (rare) have been due to kinked tubing, bent cannulas and the like. It’s kinda like Dexcom’s rubric about only putting your G6 sensor on your waist area but it’s extremely common to use the upper arm—their own promotional materials have celebrity T1’s displaying theirs with sleeves rolled up and tech support doesn’t even bother to tut-tut you about it anymore. Not to mention it’s the officially recommended location for G7.

Re iPhone : Tandem :: Apples : oranges, I think the one place where the analogy does hold was with online software updates, which Tandem was the first out of the box with correcting. I was an early adopter of the 670G and gave up on it due to its horrible interface and algorithm. Those problems were just programming not mechanical, and I was like, I’m experiencing its suckage NOW and you’re telling me it’s gonna take years to roll out a whole new pump to correct them??? You gotta be kidding me! If smartphones worked that way Apple would be bankrupt!!! I suffered bitterly from Tandem envy when they came out with remote update capability while I was still looking at years of warranty-expiration-date prison.


That’s really stupid in my less than humble opinion. I recharged my X-2 battery almost exclusively with a small rechargeable battery pack in my pocket. I hate the idea of a charger that requires me to either suspend insulin or be tethered to a wall outlet.

My experience with this as an erstwhile web developer was the very short gap between roll-out kudos and demand for new features everyone suddenly needs now that they’ve seen it live. The more impressed they are at phase one, the shorter the time to phase two. I think there’s a name for the phenomenon somewhere. Planck Length is involved.

That explains the constant constant changes of web sites and apps that are change for change sake without improvement, often to detriment.

When I was going thru the training to use control IQ I realized the software would result in increasing my A1c not reducing it. As I read about others experience with control IQ it seems they are managing the pump and not managing their diabetes. Pump is a helpful convenience and not a cure. It is possible to get excellent control without algorithms. The secret to managing T1d is what we eat. Very low carb results in being to acutely estimating bolus amounts. Reduces total amount of insulin in a day. Pumps have not changed in the 38 years I been using them. They have just become more convenient. Tandem pumps have been the least reliable pumps except for the Baxter which had a thin film keyboard. I even returned a Tandem pump that got dunked and immediately stopped working. Tandem shot themselves in the foot when they used a metal case. That is why the Bluetooth is very weak. The pump and my phone are always together in my pocket. G6 app always works but pump seldom does. Don’t blame Bluetooth.
My favorite pump was the minimed 506/508 but I hated the button batteries(3) which were expensive and hard to get. The Roche pump used a AA battery which was cheep and available everywhere.

BTW: 57 years T1d. Last 2 A1c were 5.5-5.6

I don’t know what you saw in the training that made you believe what you do about Control IQ and A1C.


The training for Control IQ definitely said that it will not respond to rising BS until it gets to 160. I use a range of 65 to 120 and wonder if I can reduce it to 65-100. The issue is if we can achieve the same result without CIQ why use it. If users work as hard managing their diet and in so doing learn how heir bodies respond then they won’t be reliant on the pump to think for them.

I was an IT consultant/Demographer/DBA/Data architect where my clients were C suite and one level below. In 46 year career never had anyone question what I did to manage t1d. Most had questions since they had relatives who were t1d or t2d. Especially when I started using the pump.

Over and over I watched pump companies bring out a pump and milk
It for profits. The money is in selling the cartages and tubing and cannulas. It is reoccurring income. Pump are a one time sale.

Ergonomic design has to be considered along with phased improvements. A pump may be a medical device but it is also a consumer device. The comparison to the iPhone is not a bad analogy. Tandem is now behind the wave in ease of use. The irony is I don’t think other pump co are any better.

Happy Holidays and a Merry Yew Near! :vulcan_salute:

Your description of Control IQ and what it does when your blood sugar rises above 160 is inaccurate, and it has no direct correlation with A1C.


Thank you for this thorough and thoughtful response! I love this conversation, and learning more about what goes into hardware and software that I live with 24/7. I appreciate the time you took!


Great insights from a true tech person! I am a lap swimmer and have hesitated taking the Tandem Tslim2 into the pool with me but may give it a try!

Whoa. I think you got the wrong impression from my comment. I would NOT recommend that kind of swimming with it. I think there’s a big difference between common swimming references and true athletic swimming. I’m NOT a lap swimmer. I’m a casual “hang out at my local hot springs” kind of swimmer, “make your way to shore after getting chucked from the raft” kind of swimmer, and a “quick dunk in the river or pond on the property to cool off in the summer” kind of swimmer.

I do take the pump in the water with me, but it’s clipped to my shoulder or a hair tie. The way I see it, when the pump is positioned high and near my face: If I’m still breathing/alive, so is my pump. I couldn’t say the same if it were on my hip in a pocket.

It’s well-protected against ACCIDENTAL exposure. Like, if I go underwater for a few moments. But I’m not keeping it underwater the entire time I’m in the water. I still make an effort to protect it. I just don’t have the same fear of water exposure others seem to express.